President Barack Obama said Tuesday it was important to work with Russia on a new generation missile shield, following his abandonment of an earlier US system that Moscow opposed, in Eastern Europe.

His comments came hours after Russia asked for guarantees from Washington that the new plan, targeting Iranian short- and medium-range missiles, would not threaten its own security.

"It is important for us to reach out to Russia and explore ways in which the missile defense configurations that we envision could potentially lead to further collaboration," Obama said after talks with NATO secretary-general Anders Fogh Rasmussen.

"We want to improve generally not only US-Russian relations, but also NATO-Russian relations, while making absolutely clear that our commitments to all of our allies in NATO is sacrosanct," Obama said.

Earlier, Russia's NATO envoy Dmitry Rogozin said at a press conference in Moscow that the Kremlin wanted guarantees the new US system "only concerns short- and long-range missiles."

"If this system is of a mobile nature, where are the guarantees... that this system will not float up to us, to our northern seas or the Baltic?"

The new plan announced by Obama envisions a mobile system of sea-based interceptors that would protect against short- and medium-range missiles from Iran, instead of Tehran's as yet to be developed long-range arsenal.

Russia had strongly opposed an earlier US plan that would have seen missile defense facilities deployed in Eastern Europe.

The earlier plan was strongly backed by Obama's predecessor, George W. Bush, and Russia welcomed the Obama administration's decision to scrap it.